Magnetrons may be used to generate radio frequency (RF) energy. This RF energy may be used for different purposes, such as heating items (i.e., microwave heating), or it may be used to generate a plasma. The plasma, in turn, may be used in many different processes, such as thin film deposition, diamond deposition and semiconductor fabrication processes. The RF energy may also be used to create a plasma inside a quartz envelope that generates UV (or visible) light. Those properties decisive in this regard are the high efficiency achieved in converting d.c. (direct current) power to RF energy and the geometry of the magnetron. One drawback is that the voltage required to produce a given power output varies from magnetron to magnetron. This voltage may be determined predominantly by the internal geometry of the magnetron and the magnetic field strength in the cavity.
Some applications may require two magnetrons to provide the required RF energy. In these situations, an individual power source has been required for each magnetron. However, two magnetrons of identical design may not have identical voltage versus current characteristics. Normal manufacturing tolerance and temperature differences between two identical magnetrons may yield different voltage versus current characteristics from unit to unit and are subject to change under dynamic operating conditions of their life cycle. As such, each magnetron may have a slightly different voltage. For example, the magnetrons may have mutually different operating curves such that one magnetron may produce a higher power output than the other magnetron. The magnetron having the higher output power may become hotter than the other, resulting in a shorter useful lifespan than the other. In addition, this may cause the power output of the magnetron producing the higher output to render the plasma in its half of the bulb to become hotter than the other, thereby producing an asymmetrical UV output power pattern.
Accordingly, what would be desirable, but has not yet been provided, is a system and method for maintaining a constant voltage and current operating point of a dual power supply for powering dual magnetrons.